Automatic control system for well drilling



Jan. 20, 1953 R. R. CROOKSTON 2,625,127

AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Filed Oct. 8, 1948 9Sheets-Sheet 1 MAIN BRAKE VALVE FEED-OFF STARTING VALVE AIR SUPPLY AIRSUPPL STEAM CHEST LINE Jan. 20, 1953 R. R. CROOKSTON I AUTOMATIC CONTROLSYSTEM FOR WELL DRILLING 9 Sheets-Sheet 2 MAIN BRAKE VALVE Filed Oct. 8,1948 EFEED'OFF STARTING VALVE 3 @M Q ff g h zvmvmx. FIG. 2. BY

BASIC UNIT I ATTORNEY.

Jan. 20, 1953 R. R. CROOKSTON AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING9 Sheets-Sheet 3 Filed 001;. 8, 1948 BASIC UNIT I Jan. 20, 1953 R. R.CROOKSTON ,6 6, 7

AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Filed Oct. 8, 1948 9sfieets-sheet 4 50 22 5 m L mm WEIGHT CONTROL UNIT IE Jan. 20, 1953 R.R. CROOKSTON 2,626,127

AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Filed Oct. 8, 1948 9Sheets-Sheet 5 llllagn'agmglllllll ma 4 I7R mlf/wm' lNVENToR.

122- Q/w g g Jan. 20, 1953 R. R. CROOKSTON- AUTOMATIC CONTROL SYSTEM FORWELL DRILLING 9 Sheets-Sheet 6 Filed Oct. 8, 1948 FIG. l3.

T N I U R R I 2 N 4 4 o n I- u m Q m V L In P P A 1 m w 4 K 0 w n a 4 24 3 5 w 2 M 2 A g 2 R I n l B 9 x M. 2 o Raf A 6 7 I H I 7 l v m 2 O A 58 L n 7 4 7 9 2 9 a 2 n R 1 a 4 2 jib/w ATTORNEY.

Jan. 20, 1953 R. R. CROOKSTON 2,625,127

AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Filed 001.. 8, 1948 9Sheets-Sheet 7 I'- r S". 2 5 D l u- LL 5: w fidfin, INVENTOR- Jan. 20,1953 R. R. CROOKSTON 2,625,127

AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Filed Oct. 8, 1948 9Sheets-Sheet 8 135 FIG. I5. 58*

221 L TORQUE CONTROL UNIT I IBSR" 13m. 47R i ll l I A 47L A 4| ATTORNEY.

Jan. 20; 1953 R. R. CROOKSTON AUTOMATIC CONTROL SYSTEM FOR WELLDRILLING- 9 Sheets-Sheet 9 Filed 001.. 8, 1948 LII Patented Jan. 20,1953 -FFICE AUTOMATIC CONTROL SYSTEM FOR WELL DRILLING Robert R.Crookston, Houston, Tex, assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware Application October s, 1948, Serial No.53,393

4 Claims.

The present invention is directed to a system for controlling theoperation of a rotary drilling rig.

In the drilling of holes in the earth for the production of petroleumand gas it is common to employ a rotary drilling rig. The drilling rigincludes a derrick provided with a crown block, a hoisting drum which ismounted adjacent the derrick, a traveling block. and a drilling linehaving one end secured to the hoisting drum and arranged to suspend thetraveling block from the crown block so that the traveling block may bemoved vertically by the hoisting drum. The traveling block is arrangedto suspend either part or all the weight of the drill stem having thedrill bit attached to its lower end. An engine is provided for rotatinga rotary table which in turn is arranged for rotating the drill stein.

Because of the limitations of the strength of materials employed in theconstruction of the equipment, the torque exerted on the drill bitshould not exceed a fixed value. When the drilling is proceedinguniformly the torque on the drill stem may be regulated by adjusting theweight carried by the drill bit. However, it sometimes happens that thetorque on the drill stem becomes excessive even though the weightallowed to rest on the drilling bit is no greater than normal.Accordingly, it is necessary to take into consideration both the weightsupported by the drilling line and the torque exerted on the drill stemby the drilling engine in order to obtain efficient use of the drillingrig Without subjecting parts of the drilling rig to an excessive strain.Ordinarily the different sedimentary deposits difier in the ease withwhich they may be drilled and this in turn causes the rate at which thehole is deepened to vary continually. ihe great length of the drill stemin proportion to its diameter gives it considerable flexibility but foreflicient operation it is desirable for the upper end of the drill stemto follow closely the action of its lower end carrying the drill bit.Accordingly, it is necessary to vary the rate at which the drill stem isbeing lowered. That is to say, continual adjustment is necessary inorder to lower the drill bit at such a rate as to maintain enough weighton the bit to insure a satisfactory rate of penetration withoutsubjecting the drill stem to an excessive amount of torque.

It is an object of the present invention to provide a system forcontrolling a rotary drilling rig which is responsive to the weightbeing carried by the drilling line and to the torque exerted by thedrilling engine.

It is another object of the present invention to provide a system forcontrolling a, rotary drilling rig responsive to the weight carried onthe drilling line and the torque exerted by the drilling en ne, e ig tcont ol ystem taking command and inactivating the torque control whiledrilling conditions are normal and the torque control taking command andinactivating the weight control when the torque exceeds a normal value.

A further object of the present invention is to provide a system forautomatically picking up the drill stem when the torque exerted on thedrill stem by the drilling engine exceeds a predetermined value.

Another object of the present invention is to provide a system forcontrolling the operation of a rotary drilling rig having means forcontrolling the rate at which the drill stem is lowered as a function ofthe weight carried by the drilling line during normal operations, meansfor holding the drill stem against vertical movement when the torqueexerted by the drilling engine on the drill stem exceeds a predeterminedfirst value and means to pick up the drill stem when the torque exertedon the drill stem by the drilling engine exceeds a predetermined secondvalue greater than said first value.

Other objects and advantages of the present invention may be seen fromthe following description taken in conjunction with the drawing, inwhich:

Fig. l is in the form of a diagrammatic flow sheet showing the controlsystem of the present application;

Fig. 2 is a front elevation, showing details of the construction ofbasic unit I of the control system;

Fig. 3 is a side view, partly in section, of basic unit I, shown in Fig.2;

Fig. 4 is an elevation, partly in section, showing details ofconstruction of a valve of basic unit I also shown in Figs. 1 and 2;

Fig. 5 is an elevation, partly in section, showing details ofconstruction of another valve of basic unit I also shown in Figs. 1 and2;

Fig. 6 is an elevation of the valve element of Fig. 4 removed from thevalve body in order to show its details of construction more clearly;

Fig. '7 is in the form of a flow sheet showing weight control unit II ofthe control system with the parts of the unit shown in the same relativepositions they occupy in Fig. 1 but somewhat enlarged;

Fig. 8 is in the form of an elevation, partly in section, showingdetails of construction of portions of weight control unit II whichparts are shown in larger scale than in Figs. 1 and 7 Fig. 9 is anelevation, partly in section, showing details of construction of anotherportion of weight control unit II;

Fig. 10 is an elevation showing the details of construction of a valveof weight control unit II also shown in Figs. 1 and 7;

Fig. 11 is an elevation showing details of construction of a valve ofweight controlunit II which valve is also shown in Figs. 1 and '7;

Fig. 12 shows the valve element of Fig. re-

moved from the valve body in order to show the details of constructionmore clearly;

Fig. 13 is in the form of a flow sheet showing quick application unitIII of the control system.

parts of the unit shown in the same relative posi-.

tions they occupy in Fig. 1 but somewhat enlarged;

Fig. 15 is in the form of a flow sheet showing torque control unit Vwith the parts of the unit shown in the same relative position shown inFig. 1 but somewhat enlarged;

Fig. 16 is in the form of a flow sheet showing pick-up unit VI of thecontrol system withthe parts of the unit shown in the same relativeposition they occupy in Fig. 1 but somewhat enlarged;

Fig. 1'? is in the form of an elevation, partly in section, showing thedetails of construction of a valve of pickup unit VI which valve is alsoshown in Figs. 1 and 16;

Fig. 18 is a view of the valve of Fig. 17 with a valve element in adifferent position;

Fig. 19 is an elevation, partly in section, showing details ofconstruction of another valve of pickup unit VII which valve is alsoshown in Figs. 1 and 16; and

Fig. 20 is a view of the valve of, Fig. 19 with the valve elementoccupying adifierent position.

It is to be remembered that in order to illustrate more clearly thesystem, separate parts thereof have not been shown in the same scale andsome parts have been shown more or less distorted. In order to aid intracing the flow-of fluids through the system, the conduit for supplyingcompressed air used as a source of power-for thepsystem is shown as-aheavy black line, pilot lines for carrying compressed air to controlelements are shown as thin black lines and conduits for carryinghydraulic liquids are shown by double lines.

Also for the purpose of simplifying the description, assemblies or unitswhich cooperate to make up the complete system have been designated byRoman numerals, important sub-assemblies included in the unitsaredesignated by letters, while the partsof the important subassembliesand the remaining parts, making up the complete system are designated bynumbers.

The complete system consists of a basic unit I which is a poweractivated means for controlling the pay-off of a .hoisting drum weightcontrol unit II whichlis capable of automatically ,;controlling basic,unitI as a function .of-the; weight supported from the hoisting drum;quick application unit III which cooperates-with basic. ,unit I andweight controlunit II- and may be considered auxiliary to weight controlunit II; drill-offunit IV which cooperates with basic unitI and'weightcontrol unit .11 andmay be considered-auxiliary-to weight-control unit-I; torque control unit V capable of automatically. controllingbasicunitI as a function of the torque exerted by the drilling engine; andpickeupunit VI which. is. capable of.- reversing the operation of basicunit. I so that the.

drill stem is picked up. when .the torque exerted by the drilling., engine, excee ds.,.a-predetermined unit. That is tosay, when-either of-theprincipal control units, weight control unit II, torque control unit Vor pick-up unit VI, takes command it has full command until itrelinquishes command to another unit. Moreover, the operator or drillermay assume the controls of basic unit I at any time and when he does sohe assumes command and the automaticoontrol units II, III, IV, V and VIare inactivated:

Considering now the entire system as shown in Fig. l, compressed air orsimilar inert gas is supplied from a suitable source, such as an aircompressor, not shown in the drawing, through main air line 56. Thehydraulic lines ML and MR carry hydraulic fluid; lines ML and AIRprovide a means whereby the weight control unit II, drill-on unit IV,torque control unit V, and pickup unit VI are able to controlautomatically the operation of the basic unit I while by-pass hydraulicline 22? connecting lines 41R and ML carries hydraulic fluid andprovides a means whereby quick application unit III applies a control tothe operation of basic unit I.

It may be mentioned that units and parts adapted to be employed in thesystem of the present applicationare described and claimed in myco-pending applications. Application Serial No. 691,486, filed August19, 1946, entitled fBrake Assembly and Serial No. 26,843,,filed May 13,1948,

entitled Power Brakes for Hoistingv Drum,de-. scribe and claimembodiments of brakes and payoff control means for a hoisting drum...Applicae.

tion Serial No. 693,992, filed August 30,,,l946,.en

titled- Valve Assembly? describesand. claims an, embodimentsuitablefmuse asmaster valve as: sembly C while application Serial No. 26,842,filed,

May 13, 1948,. entitled fFluid Control System describes and claimsianarrangement suitable for use as main brake valve 53.- Embodiments ofweight control ,unit II, quickapplication unit III and drill off unit IVare described and claimed in my copending application, Serial No.70,765, filed January 13, 1949, entitled Automatic Weight ControlDevice.

The'basic unit I will now bev described in detail. The importantelements of this unit are shown in'the relative positions they occupy inthe complete system in Fig.1 while details of construction incIudingthehoisting drum are shown in Figs. 2 and 3 and details of construction ofvalves of this unit areshown in Figs. 4, 5, and6.,

Brake band assemblies AL and AR are mounted on :hoisting drum 2| forlimited arcuate movementiwith respect thereto. Lever ll is mountedonframe. 20 and is arranged to pivot aroundits center I2 and serveslasa, means for connecting the brake band assemblies .to the frame with oneend connected to'brakebancl assembly AL through linkage 13L .and itsother end connected to brake band assembly AR through linkage 3R;

Brakeband assembly. AL consists of brake band 22! with power assembly BLmounted thereon and brake band assembly AR consists of a similar brakeband 23 with power assembly BR mounted thereon. The power assemblies BLand BB. are identical and each consist of brake cylinder 24, piston 25,piston rod 26, and spring 2?. The piston is slidably arranged in thecylinder and the cylinder is mounted on one end of brake band 23 whilethe. end of pistonrod 26 is secured to the other; end of the, brake bandthrough linkage 2a. The spring 2? isarranged in the cylinder betweenpiston 25 and the pistonend of the cylinder so that it biases the pistontoward the piston rod end of the cylinder.

In the power assembly BL the head end of cylinder 24 has a portconnected to inlet line 28L for the admittance and release of compressedair. In the power assembly BR the cylinder 24 has a port connected toinlet line 23R for the admittance and release of the power fluid.

The brake band assembly AL i also connected to the frame 20 by ahydraulic assembly consisting of cylinder 41L with piston 42L slidablymounted therein and connected through piston rod 43 and linkage 44 tothe brake band 23. Brake band assembly AB is similarly attached to frame20 through a hydraulic assembly consisting of cylinder MR and piston 42Rslidably mounted therein and connected through piston rod 43 and linkage44 to brake band 23.

The cylinders ML and MB of assemblies AL and AR respectively defineports at their piston ends and head ends. The ports of the piston endsof the cylinders are fluidly connected by conduit 45. The head end ofcylinder 4IL is connected to conduit 41L and the head end of cylinder HRis connected to conduit 41R, these conduits being connected by amanifold consisting of lines 13, 19 and 16 and by by-pass line 221. Line41R is provided with diaphragm-operated valve I3'IR and similarly line41L is provided with diaphragmoperated valve I3'IL.

In effect the cylinder and piston assemblies 4IL, 42L and 41R, 42Rcomprise a multi-cylinder pump mechanically connected to hoisting drum20.

A pilot valve 48L is mounted on cylinder ML of assembly AL and isarranged to be operated by contact with activator 49L. Similarly, apilot valve 48R is mounted on cylinder MR of the assembly AR and isarranged to be operated by contact with activator 49R.

Basic unit I also includes a master valve assembly C having valve bodies29L and 29R and diaphragm 32. The parts of the two valve bodies 29L and29R have the same relationship as the right and left hands of a person.

Valve body 29L defines an inlet port 33L, an outlet port 34L, exhaustport 35L and pilot line port 38L. Valve element 30L is slidably arrangedin valve body 29L and has a rod 3iL connected thereto and projectingthrough a packed opening in the right end of the valve body. Valveelement 30L defines transversely extending passages 36L and 31L. Whenvalve element 33L is in its left position, passage 36L fluidly connectsinlet port 33L with outlet port 34L and when it is in its right positionpassage 31L fluidly connects outlet port 34L with the exhaust port 35L.

Valve body 29R has a valve element 33R slidably arranged therein with arod 3IR connected thereto. Valve body 23R defines inlet port 33R,

- outlet port 34R, exhaust port 35R, and pilot line port 38L. Valveelement 30R defines passages 36R and 31B. When the valve element 36R isin its right position, passage 36R fluidly connects inlet port 33R withoutlet port 34R and when the valve element is in its left position,passage 31R fluidly connects outlet port 34R with exhaust port 35R.

Compressed air is supplied from main air line 50 through branch 39 to ableeder type relay valve l9 which in turn is connected by branch lines40L and 40R to inlet ports 33L and 33R, respectively. A diaphragm 32 isarranged between valve bodies 29L and 29B. with one side of thediaphragm connected to rod 3IL and the other side connected to rod 3 IR.

Air to activate master valve assembly C is sup plied by pilot lines 68,HR and ML. Pilot line 68 is connected to diaphragm 32. Pilot line I'ILis connected to pilot line port 38L of valve body 29L and pilot line HRis connected to pilot line port 38R of valve body 29R.

When the hoisting drum 2! is paying out drilling line as it is normallyoperated, the operation of master valve assembly C is controlled bypilot valves 49L and 49R. The fluid connection between master valveassembly C and pilot valves 49L and 49R. is through valve N which formsa part of the pick-up unit IV but this unit is inactivated when themovable part of valve N is in the position shown in Fig. 15. Tracing theflow when the pick-up unit IV is inactivated and the valve element ofvalve N is in the position shown in Fig. 17, pilot valve 48L isconnected through pilot line 56, double check valve 202, pilot line 203,double check valve 204, pilot line 235, valve N and pilot line HR to theend port 38R of master valve assembly C. Similarly, pilot valve 48B isconnected through pilot line 2, valve N and pilot line llL to port 38Lof valve body 29L of master valve assembly C.

The means for manually controlling basic unit I are main brake valve 53,which is of the bleeder regulator type, manually adjustable valve 54,and feed-off starting valve 55. The inlet of main brake valve 53 isconnected through branch line 50' to main air line 50. The outlet ofmain brake valve 53 is connected through pilot line 6! to an inlet ofdouble check valve 51 and through pilot line BI and pilot line 64 to thediaphragm of diaphragm valve 55. The inlet of manually controlled valve54 is connected through branch line 58 to main air line 50 while itsoutlet is connected through pilot line 62 to an inlet of double checkvalve 57. The outlet of double check valve 51 is connected through pilotline 63 to bleeder type relay valve 19. The inlet of diaphragm valve 56is connected to main air line 5!] by branch line while its outlet isconnected by pilot line 69 to an inlet of double check valve 61 and bypilot line 69 and pilot line 2H! to diaphragm 242 of double diaphragmvalve Q and diaphragm 245 of double diaphragm valve S. The outlet ofdouble check valve 6'? is connected through pilot line 68 to diaphragm32 of master valve assembly C.

Feed-off starting valve 55 has its inlet connected by branch line 59 tomain air line 50 and its outlet connected to pilot line 65, double checkvalve 204, pilot line 235, valve N and pilot line IlL to inlet 38L ofmaster valve assembly C. Feed-off starting valve 55 is also connectedthrough pilot lines and 206 to diaphragm 24! of double diaphragm valve Qand diaphragm 244 of double diaphragm valve S.

In order to maintain a supply of hydraulic fluid in the system tocompensate for loss of fluid, as by leakage and the like, a reservoir232 has an outlet line 233 fluidly connected to line of the manifoldwhich connects hydraulic lines 43L and 41R. This manifold consists ofline 13 provided with check valves 14 and 75, line l6 provided withcheck valves 11 and i8, and line 19 containin needle valve Ill. The line16 to which reservoir 233 is connected is the low pressure side of valveH in the manifold. The inlet 234 of the reservoir may be connected toany suitable source of sup-ply of hydraulic fluid, not shown on thedrawing. The fluid in reservoir 232 i maintained under 'aconstantpressure. -In'the drawing 'the constant pressure is maintainedon reservoir 232 by a branch line 235 containing-regulator 236 whichconnectsthe upper portion of the reservoir with main airline 59. As asafety feature, a diaphragm valve 23"! has its inletin communicationwith main air line 59 and its outlet connected through pilot line I8,double check valve 61 and line 68 to diaphragm 32 of master valveassembly C of basic unit I. The diaphragm of valve 231 is connectedthrough branch line 238 to line 233 of the hydraulic system. With thisarrangement any dangerous loss of pressure from the hydraulic systemwill allow diaphragm 231 to open which allows compressed air from mainline 50 to escape through pilot line I8, double check valve 61 and line68 to diaphragm 32 of master valve C which in turn activates the mastervalve C and stopsrotation of the hoisting drum.

The weight control unit II is shown in the position it occupiesinth'ecomplete system in Fig. 1 and is shown separately in Fig. 7 whiledetails of construction of parts-thereof are shown in Figs. 8 to 12,inclusive.

The principal part of Weight control assembly II are master'valve E,master valve F, motor and bleeder assemblies GL andGR, cylinder andpiston' assemblies HL and HR and a needle J of a weight indicator. It isto be understood that several types of weight indicators arecommercially available. Any of the types provided with a weightindicating needle may be used, however, inorder to simplify the'showingin this application,'only the needle of a weight indicator is shown inthe drawing.

Compressed air for operating weight control assembly II is supplied frommain air line 58 through branch line I6 controlled by diaphragm valve I5and through branch line Ilii controlled by needle valve I I1. Controlmeans are provided so that diaphragm valve I5 is controlled by theoperation of main brake valve 53 and feed-off starting valve 55. Thediaphragm of valve I5 is connected through pilot line Iii and pilot lineI3I to the outlet of double check valve I36. An inlet of double checkvalve I30 is connected to double diaphragm valve Q which, in turn, isconnected through line 287 to main air line 58. Diaphragm 2M of doublediaphragm Q is connected through pilot lines 206 and 65 to feed-oilstarting valve 55 while diaphragm zsz of double diaphragm valve Q isconnected through pilot lines 2 I and 69 to diaphragm valve 56.

Double diaphragm Q is of the 'bleeder type consisting of valve body 49and diaphra-g-ms 2M and a 242. It also includes a valve element,notshown in the drawing, operated by di-aphragms 2M and 242. Valve Q isopened by operation of main brake valve 53 which allows the passage ofair to diaphragm valve 56 from main air line 59 through line 60, pilotlines 89 and 2m to dia phragm 242 of valve Q. Valve Q is closed byoperation of feed-off starting valve 55. When valve Q is closed and thevalve elements of double check valve I30 permit communication betweendiaphragm valve I and valve Q, air is bled from pilot lines MI and I3and allows valve I5 to open and supply air to weight control unit II.When valve Q is open compressed air is allowed to pass from main airline 50 to pilot line 207, valve Q, double check valve I39 and pilotlines I3I and MI to the diaphragm of valve I5, closing this valve andpreventing the supply of compressed air to power weight control assemblyII.

'The weight control unit II is arranged to control the flow of hydraulicfluid through the manifold consisting of lines 13, I5, and E9 in whichmanifold lines 53 and "It are connected to hydraulic lines 37R and ML.

Needle valve I5! is arranged to control-the flow of fluid through lineI9 and is provided with a valve stem II on which is mounted a toothedvalve wheel 12. Check valves '15 and T5 are arranged in line 13 andsimilarly check valves I1 and 18 are arranged in line H5. The manifoldwith its check valves is arranged so that fluid flow through needlevalve lIl is unidirectional at all times irrespective of the changes inthe direction of flow in lines ML and 411%. The resistance of needlevalve 70 to flow is slightly different when the direction of flow isreversed and in order to insure uniform operating conditions it isdesirable to connect the valve through the conduits ML and AIR by thetype of manifold shown rather than by using a single line containing thevalve. However, it will be understood that with respect to the principleinvolved in the control system, a single valve could be used to connectthe conduits l'IL and l'IR.

Master valve assembly l5. consists of a valve body ill which defines endpilot ports 82L and 823. It also defines an inlet port 83, exhaust portsML and MR and outlet ports 85L and 85R. A valve element 85 is slidablymounted within valve body 8i and defines passages 81, 88,- and-89. Whenthe valve element 86 is in its right position with respect to the valvebody, passage 88 connects inlet port 83 with outlet port 85R whilepassage 89 connects outlet port 851.. with exhaust port 84L. When thevalve element 86 is in its left position, passage 88 connects inlet port83 with the outlet port 85L and passage 37 connects outlet port 85R withexhaust port 84R.

Master valve F consists of a valve body '9! which defines end pilotports 32L and SEE. It also defines an inlet port 93, exhaust ports 94Land 94B and outlet ports 95L and SEE. A valve element 95 is slid-ablymounted within valve body 52: and defines passages 91, 93, and 99. Whenthe valve element 96 is in its right position with respect to the valvebody, passage 93 connects inlet port 93 with the outlet port 95R whilepassage 99 connects outlet port 95L with exhaust port 94L. When thevalve element 96 is in its left position passage 98 connects inlet port93 with outlet port 55L and passage 91 connects outlet port 95R withexhaust port 94R.

Each air motor and valve assembly GL and GR consists of a body Hill inwhich is sli-dably arranged a piston IiII connected to piston rod I02with a spring I63 arranged between the piston and the head end or" thecylinder to bias the piston away from said head end. -Each valve bodyalso defines an end port and a side port.

The end port of body I'Ilil of valve assembly GL is connected by conduitI ML with the outlet port 95L of valve F and the side port of this bodyis connected through conduit 1551- to pilot port 82L at valve E.Similarly, the end port of body Ill!) of valve assembly GR is connectedby conduit MAR to outlet port 95R of valveF and its side port isconnected through pilot line 35R to pilot port 32B of valve E.

Valve E also has its outlet port 85L connected through conduit It-t toport 92R of valve F and its outlet. port 85R connected through conduitIt! to port 92L of valve F. Compressed air from main air line 50 issupplied throughline IB- and branch line I 08 to inlet port 83 of valveE and 9 through line I6 and branch line I09 to inlet port 93 of valve F.

A bleeder valve I IIlL is mounted on piston rod I92 of assembly GL andbleeder valve IIEIR is mounted on the piston rod of assembly GR.

Assemblies HL and HR each consist of a cylinder III with a piston H2slidably mounted therein. The piston is attached to piston rod H3 and aspring H4 is mounted in the cylinder around the piston rod between thepiston and the valve head of the cylinder to bias the piston away fromthe head end of the cylinder. The piston rod carries a pawl or ratchetmember I I5 adapted to engage with toothed wheel 22 which activates theneedle valve I0.

Compressed air from line 50 is supplied to bleeder valve IIIIL by way ofconduit H6 controlled by valve H1 and branch line H8 containing checkvalve H9. Compressed air is applied to the bleeder valve IIUR from themain air line through conduit H6 and branch line I25 containing checkvalve I2I. Compressed air for operating unit HR is withdrawn from branchline I I8 through conduit I IZR. while air from operating unit I-IL iswithdrawn from branch line I29 through conduit I22L. A diaphragm valveI23 is mounted in branch line I20 between conduit I22L and bleeder valveHER. and a pilot line I2 5 connects to branch line I20 at a pointbetween diaphragm valve I23 and bleeder valve IlIlR.

The needle J of a weight indicator (not shown in the drawing) is mountedadjacent the bleeder valves IIIlL and IIDR. The needle is arranged sothat when the weight carried by the drilling line is less than apredetermined fixed value, the needle will be moved adjacent one of thebleeder valves, say valve IIflR, while if the weight is in excess ofpredetermined fixed value the needle will be moved adjacent the otherbleeder valve I IBL. If the weight is within the desired range, needle Jwill be between the bleeder valves I ISL and IIDR. When away from itscenter position, it makes contact either with valve IIIIL or with valveI IBR every time the piston of the air motor reciprocates, and this inturn allows air to bleed from the bleeder valve.

The quick application unit III is shown in the position it occupies withrespect to the other portions of the complete system in Fig. '7, and isshown on a larger scale in Fig. 13.

The quick application unit III consists of bypass line 221 provided withdiaphragm valve 223, the diaphragm of which is connected to motor andvalve assembly GL and actuator assembly HR. Pilot line 222 containingneedle valve 223 and check valve 224 connects the diaphragm of valve22"! to line H8 at a point in line H8 between check valve I59 and branchline I22R. At :a point in line 222 between check valve 222 and thediaphragm of valve 228, a branch line 225 controlled by needle valve 226connects said line 222 to main air line 50. By-pass line 22'! isconnected in parallel with the manifold consisting of lines I3, 16 andI9 (containing needle valve I I) inasmuch as by-pass line 227 and themanifold each fluidly connect hydraulic lines 41R with line 47L.Diaphragm valve 228 is adapted to assume either a full open or anentirely closed position. By-pass line 221 is provided with a needlevalve 229 to allow the rate of flow to be adjusted when diaphragm valve228 is in its open position.

The drill off assembly IV which cooperates with basic assembly I andweight control assembly II is shown in the position it occupies in thecom- 10 plete system in Fig. 1 with the parts shown on a larger scalethan Fig. 14. Drill-ofi unit IV consists of diaphragm valve T connectedto double check valve I32, double check valve I34, diaphragm valvesI3'IR and I3'IL and diaphragm valve I23.

The inlet of diaphragm valve T is connected to main air line 50 throughbranch line 2 I5. The outlet of valve T is connected through line 2I5 toan inlet of double check valve I32. The outlet of double check valve I32 is connected through line I 33 to double check valve I32 whose outletin turn is connected through line I35 and branch lines ISBR and I35L todiaphragm valves I3'IR and I3'IL, respectively, which valves control theflow of hydraulic fluid through hydraulic lines 41R and 4'IL. Thediaphragm of diaphragm valve T is connected through pilot line 2H,controlled by needle valve or orifice 2E8, to main air line 52. A branchpilot line I24 containing a needle valve H9 and check valve 225 connectsline 2H at a point between needle valve 2I8 and the diaphragm of valve Twith line I26, which line connects bleeder valve Him. or weight controlunit II with a source of compressed air. The check valve 220 is arrangedin line I24 to prevent flow of air from line I29 into line I24 in casethe pressure in line I24 becomes lower than that in line I29. Diaphragmvalve I23 is counted in line I26. The diaphragm of this valve isconnected through pilot line 22I to line I35. The torque control unit Vand the pickup unit VI are activated by fluctuations of pressure in thesteam chest of the drill engine (not shown in the drawing). As indicatedin Fig. 1, line I38, the steam chest line, is adapted to be connected tothe steam chest of the drilling engine and is controlled by doublediaphragm valve S. The torque control unit V is activated byfluctuations in the steam chest by the connection of diaphragm I25 ofdouble diaphragm valve K with steam chest line I38, while the pickupunit VI is activated by the connection of diaphragm I51 of doublediaphragm valve M with steam chest line I38.

Double diaphragm valve S is of the bleeder type and consists of valvebody I43 with diaphragms I44 and I45. It also includes the valve element(not shown in the drawing) activated by the diaphragms 244 and 245.Diaphragm 244 is connected through pilot lines 255 and 65 to feed of]?starting valve 55. Diaphragm 245 is connected through pilot lines 2IIiand 59 to diaphragm valve 56 which is actuated by main brake valve 53when the pressure applied against diaphragm 244 is greater than thatapplied against diaphragm 245 valve S is opened. When the pressureapplied against diaphragm 245, as by the opening of main brake valve 53,is greater than the pressure applied against diaphragm 244, valve S isclosed and bleeds on the air pressure from diaphragms I28 and I5I ofdouble diaphgram valves K and M, respectively. The torque control unit Vis shown in the position it occupies in the complete system in Fig. 1and is shown separately and on an enlarged scale in Fig. 15. I

The torque control assembly V includes the double diaphragm bleeder typevalve K having body I25 and diaphragms I26 and I2'I adapted to operatethe movable valve element (not shown in the drawing). The inlet of valvebody I25 is connected through branch line I28 to main air line 55. Theoutlet of valve body I25 is connected through line I29 to an inlet ofdouble check valve I30. It has heretofore been men- 11 tioned that theoutlet of double check. valve I36 is connected through pilot lines I3I.and MI to diaphragm valve I5- The connection of double diaphragm valve Kto aninlet of double check valve I30 and through, these. pilot lines to.diaphragm valve I5 causes weight control unit II to be activated whentorque control unit III takes command. Pilot line I3I is also connectedto an inlet of double check valve I32 which has its outlet connectedthrough conduit I33 to an inlet of double check valve I36. The outlet ofdouble check valve I34 is connected through pilot line I 35 and branchlines I36L and I36R to diaphragm valves I31L and I313 which control theflow of hydraulic fluid in lines 41L and 41R, respectively.

The pickup unit VI is shown in the position it occupies in the completeassembly in Fig. 1 and is shown separately on an enlarged scale in Fig.16 with certain valves of the unit shown in section in Figs. 17, 18, 19,and 20.

The principal parts of pickup unit VI are double diaphragm valve M,master valve N, master valve and pump P. Compressed air for supplyingpump P with power is supplied to pickup unit VI from main air line 55through diaphragmregulated valve I56. Compressed air for operating thecontrol mechanisms may be supplied from main air line 56 either throughpilot I53 controlled by double diaphragm valve M or through pilot lineI56 controlled by manually operated valve I56. The outlet of valve N isconnected through pilot line I55 to an inlet of double check valve I55,while pilot line I56 is connected to the other inlet of double checkvalve I55; Thus, the pickup unit VI may be activated either'by thedouble diaphragm valve M or by manually controlled valve I56.

Double diaphragm valve M is of the bleeder type with a valve body I55and diaphragms II and I52 adapted to operate the movable valve element(not shown in the drawing). Diaphragm I5I of valve M is connectedthrough line I38 to the steam chest of the drilling engine (not shown inthe drawing). Diaphragm I52 of valve M is connected to a supply of airat a constant pressure; in the embodiment shown this is provided byconnecting it to main air line 50 through pilot line'23IJ'provided withregulator 23 I.

It has been heretofore mentioned that air for poweringthe pickup unit VIpasses either through valve M or valve I56 t double check valve I55 .Theoutlet of double check valve I55 is connected through pilot line I51 topilot line I58. Pilot line I58 has one end connected to an inlet ofdouble check valve I34 and the other end connected to the diaphragm ofvalve I59. Pilot line I 58is connected through pilot line I65 to thediaphragm of diaphragm valve I65; through pilot line I61 to end port I1Iof master valve N and through pilot line I69 to the diaphragm ofdiaphragm valve I68. Diaphragm valve I65 is of the bleeder typeandnormally open. Pilot line I58 is also connected through pilot line I6Icontaining an orifice. or bleeder valve I62 to the diaphragm ofdiaphragm valve I66, through pilot line 206 to the inlet side ofdiaphragm valve I 66.

Double check valve I34 has its outlet connected through pilot line I35and branch lines I36R and [36L to the-diaphragms of diaphragm valves131R, and I31L, respectively,which control the flow of fluid .throughhydraulic lines 41R and Diaphragm valve I60 has its outlet connectedthrough pilotline 2III to an inlet of double, check valve 202. Line 66connects the other, inlet side of double check valve 2II2 with pilotvalve 43L of basic unit I. The outlet of double check. valve 202 isconnected through pilot line 2Il3 to an inlet of double. check valve264. The other inlet of double check valve 204 is connected throughpilot line 65 to feed on" starting valve 55. The outlet of double checkvalve 26-4 is connected through pilot line 265 to port I13 of valve N.

Master valve N includes a valve body I10 which defines an end port HIand side ports I12, I13, I16, and I15. Slidably mounted within the bodyis valve element I16 defining passages I11, I18, and I19. Spring I36 isarranged within the valve body to bias movable valveelement I15 to theleft. When the valve element is in its left position, passage I18connects port I13 with port I16 and passage II'I connects port I12 withport I15. When thevalve element I15 is in its right position, passageI19 connects port I 12 with port I13 and passage I18 connects port I16with port I15.

Master valve 0 consists. of a valve body ItI which defines end portsIIIZand I33 and side ports $5,155, I86, and I81. Valve element I68 isslidably arranged thereinand defines passages I35, I90, and I9I. Whenvalve element I58, is in its right position passage I89 connects portI84 with port I and passage I connects port I36 with port I81. Whenvalve element I88 is in its left position, passage I65 connects port I85with port I86, while passage I9! connects port I84 with port I81.

Master valve N is fluidly connected to master valve 0 of pickup assembly"I as Well as to master valve assembly C of basic unit I. Master valveassembly 0 is fluidly connected to hydraulic line's 51R and 41L and topump assembly P. The movement of the valve elements of valve 0 iscontrolled by master valve N.

Pump P may be a reciprocating pump of the conventional type with a powerend I52 anda pumping end I93. The flow of air into pump P is controlledby diaphrgam valve I55 in air supply line 50. Hydraulic. line I connectsport I85 of valve 0 with the inlet of pump P and hydraulic line I95connects the outlet of the pump with port I81 of valve 0.

Air applied through pilotline I61 to end port III of master valve Nserves to operate the valve. The movement of master valve .0 iscontrolled by air pressure exerted through end ports I82 and I63 at theends of the valve. End port I 32 of master valve 0 is connected to portI13 of master valve N by means of pilot line 209, controlledIbydiaphragm valve I68, and pilot line 205. End'port I83 of master valve 0is connected to port I14 of master valve N through pilot line 212, whichis controlled by diaphragm valve l65, and pilot line 2 I2. Port I12 ofmaster valveN is connected through pilot line I1L to valve element 29Lof master valve assembly C of basic unit I. Valve 0 has its port I34connected through branch line 2I3 to line 41L carrying hydraulic fluid.Similarly, port I86 of valve 0 is connected through branch line 2 I5,Wich is controlled by diaphragm valve I63, to line 41R which carriedhydraulic fluid. I

The operation of the several portions of, the assembly and theircooperation with one another will now be described.

Operation'of basic unit I The operation of basic unit I will firstbeconsidered. Briefly, basic-unit I is a brakesystem and feed-:ofi.mechanism. An air system is 'arl3 ranged to operate alternately theright and left brake bands during feed-off while drilling with the speedof rotation of the brake drums regulated by the hydraulic system. Itwill be assumed that the parts are in the relative positions indicatedin Fig. 2 with drum 2| moving in counterclockwise direction (as viewedin Fig. 3) under the load supported by cable 22, with the brake bandassembly AL engaged with the brake drum 2| and moving with it whileassembly AR is loose on the brake drum and moving in the oppositedirection from brake band assembly AL. Main brake valve 53 is in itsnormal closed position and valve 54 is in the open position, thesecontrol valves having previously been given these settings by theoperator. With main brake valve 53 closed and valve 54 open, air flowsfrom main line 55 through branch line 58, valve 54, pilot line 62,double check valve 51 and pilot line 63 to relay valve 19. The air flowsthrough the double check valve 51 into line 63 because the slidableelement of the double check valve is forced to the left extremity ofvalve 51 because the pressure in line 62 is greater than the airpressure in line Bi line 6| having been bled by main brake valve 53which is of the bleeder regulator type. Relay valve I9 is held open bymeans of the pressure exerted through pilot line 63. With relay valve I9open, air flows from main air line 59, through line 39 and valve Hi tobranch lines ML and 40R, thence to valve bodies 29L and 29R,respectively, of master valve assembly C. Slidable element 30L is inextreme left position in valve body 29L and consequently the air fromline 40L flows through port 33L, passage 36L, port 34L and line 28L tothe piston rod end of cylinder 24 of power unit BL; this causes airpressure to be exerted against the piston rod end of piston 25 andmaintains brake band assembly AL tight on drum 2 I. While slidableelement L of valve body 29L is in its extreme left position, the valveelement 30R in body 29R is also in its extreme left position. With valveelement 30R in this position air is prevented from passing from line 40Rto the power assembly BR but instead the piston rod end of cylinder 24is connected to the atmosphere through line 28R, port 34R, passage 31Rand exhaust port 35R; this allows spring 2! to force the piston 25toward the piston rod end of power assembly BR, thus maintaining brakeassembly AR loose on brake drum 2|. While brake band assembly AL is thusengaged and brake band assembly AR is disengaged, the piston 42L ismoving upwardly while piston 42R is movin downwardly. The upward motionof the piston 42L is produced by the pull of cable 22 on brake drum 2|,causing rotation thereof. Inasmuch as brake band assembly AL is engagedwith brake drum 2 I, the brake band assembly AL is moving arcuately withthe drum, thus causing the piston 42L to move upwardly in its cylinderML. As previously pointed out, cylinders ML and MR contain fluid and thelower ends of the pistons are fluidly connected by line 45 while thehead ends of the cylinders are fluidly connected through line 41R and MLand the manifold consisting of lines 13, I6 and 19. As the piston 42Lmoves upwardly, the fluid contained in the upper portion of the cylinderof this assembly passes through line L, check valve 15, branch line I3,line 19 controlled by needle valve 10, branch line 16, check valve 11,and line HR to the upper portion of the cylinder ofassembly DR, forcingthe piston 42R of the assembly downwardly therein. Since assembly AR ismechanically connected to piston 42R, the assembly AR is forced to movearcuately to follow the piston 42R. As brake band assembly AR reachesthe end of its downward stroke, actuator 49R contacts valve 48R, therebyopening valve 48R momentarily, which in turn allows compressed air toflow from main air line 50, branch line 5| and branch line 52R throughthe valve 48R and pilot line 2!], master valve N and pilot line IIL toport 38L of valve body 29L to push movable element 30L to its extremeright position from inlet port 38L; the thrust is transmitted throughrod 3lL, diaphragm 32 and rod 3IR to element 30R so that at the sametime element 30R is also moved to its extreme right position. Upon thismovement of element 30L, flow of air from branch line 40L through valvebody 29L is terminated and the piston rod end of cylinder 24 of assemblyBL is bled to the atmosphere through port 34L, passage 31L and exhaustport 35L; this allows the spring 21 of assembly BL to drive the piston25 of this assembly toward the piston rod end and releases brake bandassembly AL from the brake drum 2|. The simultaneous movement of element30R to its extreme right position in valve body 29R allows air to flowthrough air line 40R, port 33R, passage 3BR, outlet port 34R and line28R into the piston rod end of the cylinder 24 of assembly BR, therebydriving the piston 25 of this assembly toward the head end of thecylinder and tightening brake band assembly AR on brake band 2 I.'Iightened brake band assembly AR rotates with brake drum 2 1, therebycausing the piston 42R to move upwardly; simultaneously piston 42L isforced downwardly so that brake band assembly AL, mechanically connectedto piston 42L, is moved arcuately in the direction opposite from thedirection of movement of assembly AR. As brake band assembly AR rotateswith drum 2 I, piston 42R moves upwardly toward the piston rod end ofcylinder 41R. While the piston 42R is moving upwardly, piston 42L ismoved downwardly, this downward movement of piston 42L being caused bythe flow of fluid from cylinder MR through conduit R, the manifoldincluding lines 13, 19 and 16 and hydraulic line L to piston 4|L.Inasmuch as brak band assembly AL is fiuidly connected to the piston42L, it is caused to move arcuately in cooperation with this piston. Themovement of brake band assembly AL in due course brings actuator 49Linto contact with pilot valve 48L and opens this valve momentarily. Theopening of pilot valve 48L allows air to flow through pilot line 65,double check valve 202, pilot line 203, double check valve 204, pilotline 205, valve N and pilot line HR which, in turn, causes movableelement 30R in valve body 29R of master valve assembly C to move fromits extreme right position to its extreme left position with themovement of this element transmitted through rod 3|R, diaphragm 32 androd 3IL to movable element 30L in valve body 29L to move this elementalso from its extreme right position to its extreme left position; thischange in the setting of master valve C admits air to the piston rod endof cylinder 24 of power unit BL and allows air to exhaust from cylinder24 of power unit BR thereby tightening brake band assembly AL andreleasing brake band assembly AR, thus allowing the cycle heretoforedescribed to be repeated.

The linkage including pivoted lever ll connected to brake bandassemblies AL and AR.

2 respectively, through linkages BL and I3R is a safety feature. If abreak should occur in the hydraulic system and the mechanical linkageWere not provided, the pistons 42L and 423 could move to the head endsofpistons ML and MR simultaneously; this would allow a considerable shockto be placed on the drilling line 22 as well as on other parts of thesystem. The arrangement of the'pivot ed lever ll mechanically connectedto both brake band assemblies AL and AR insures that even though a leakor break should develop in the hydraulic system, the piston 42L and 42Rare maintained in a fixed position in relationship with each other. Itis to be mentioned that th pistons lZL and 42B do not-follow themovement of theends of pivotedlev'er I I exactly, but any slightdiscrepancies in-this respect may be taken care ofby reservoirs of variablecapacities, such as reservoir 232, in the hydraulic system.

The manipulation of valve members by the driller in order to control themovement of the hoisting drum will now be described. If it is desired tohold thehoisting drum 2| stationary, this may be done by moving theoperating lever of the main brake valve 53 to open the valve which inturn allows air pressure to open diaphragm valve 56; main air pressurethen enters pilot line 69 and passes through double check valve 57 andbranch pilot line 68 to expand diaphragm member 32 which, in turn, moveselement 30L in body 29L toits extreme left position and element 30R invalve body 29R to its extreme right position; opening main brake valve53 also allows air to fiow through double check valve assembly 51 andpilot line 531: relay valve [9 and opens it whereby air'from the mainair line 50 is given access to inlet ports 33L and 33B of valve body 25Land 29R. The expansion of diaphragm element'lig together with admissionof air through relay valve [9 tovalve bodies 29L and 29R allowscompressed air to pass through branch line 45L, passage 36Land to line28L to th piston rod end of the cylinder of the assembly BL and throughconduit 45R, passage 36R and conduit 281?, to the piston rod end of thecylinder of -asseinbly BR; this tightens brake band assembliesAL and ARsimultaneously andprevents any rotation of drum 2!.

The opening of main brake valve 53 'which in turn, opens diaphragm valve56 also vallows air to pass from main air line 55 through branch linefiilydiaphragm' valve 56 ,pilot lineBQ, and pil ot line 2H! so thatcompressed air is applied to diaphragm 242 of double diaphragm valve Qand diaphragm 2 35 of double diaphragm valve 5; this opens valve Q, ifit is not already open, and air is supplied to the 'pilot linesconnected therewith so that pickup unit II, quick application unit IIIand drill-01f unit-IV, auxiliary thereto, are inactivated, and hydraulicvalve l 31R and IS'IL are closed. This closes double diaphragm valve S,if it is .not already closed, and pressure is bled from diaphragm I25 ofdouble diaphragm valve Kand from diaphragm [5| of double diaphragm valveM so that torque control unit V and pickup unit VI are (alsoinactivated. In other words, when the operator closes thernain brakevalve- 53, he not only sets the brakes but also inactivates theautomatic control-equipment to insure-that the operator, and only theoperator, exercises command of the system at this time.

As long as the operator holds main brake valve 53 in the open positionthe drum is held sta tionary but if he releases the handle so that itcan return to its neutral position, valve 53 which is of thebleeder-regulator type, bleeds ofi the air from diaphragm 32 andrelayvalve I9 thereby releasing the brakes- Accordingly, if' thedrillerwishes 'to leave the brakes 'set when he Walks away from the main brakevalve 53;, it is necessary for him to open hand-operated valve 54 beforereleasing the operating handle of main brake valve 53. If valve 5 3 isopen, then release of the operating lever of main brake valve 53 allowscompressed air to pass from main air line 58 through branch line 53,valve 54 and pilot line 62, double check valve 57 and pilot line 63 tomaintain pressure on relay [9. After the brakes have been set by theexpansion of main brake valve 53 the diaphragm 3 2 is extended andremains extended whilethe operator changes his method of control byopening valve 54 and releasing the operating handle of main valve 53.

The manipulativev steps for bringing the unit from rest to normalrotation under load are as follows:

If valve 54 has not been opened upon the operation of main brake valve53, it is now opened and the operating handle of main brake valve 53 isreleased and allowed to assume its neutral position. These steps allowthe double check valve 5'! to respond topressure in line 62 with airpassing through line 58, valve 55, pilot line 62, double check valve 51,and pilot line 63 to relay l9. The return of the end lever of main brakeband 53 toneutral position allows the air to be bled rrom pilot line 6|which, in turn, causes diaphragm valve 55 to close. valve elements 36Land 30B, of master valve assembly C are in their proper positions, it isdesirable to move these elements in a known posi: tion at that time;this could be done by operating manually either valve 58L or 58R but,for convenience, valve 55 is connected in parallel with valve 43L andoperation of this valve allows air to pass from main air line 55, branchline 59, valve 55, pilot line 65 to double check valve 204, Theadmission of pressure through pilot line 65 controls the position ofdouble check valve 204 and allows air to pass on through pilot line 205,valve N and pilot line HR to the inlet port 38R of master valve assembly0 which causes valve elements 35R and 30L of master valve assembly C tobe moved to their extreme left positions. In other words, a momentaryopening of valve 55 by the operator positions valve elements 30L and 30Rto insure that air will flow into the rod end of the cylinder ofassembly BL to tighten brake band assembly AL and that air is exhaustedfrom the rod end of the cylinder of assembly BR to allow the release ofassembly AB, from hoisting drum 2 l. The momentary opening of valve 55by the operator is the last manipulative step in the starting operationand the assembly then pays out line or walks at a speed which iscontrolled by the rate hydraulic liquid flows through needle valve 16 aslong as drilling conditions remain normal. 7

If it is desired to release both brake band assemblies AL and ARsimultaneously, as when running a drill stem into a borehole, this maybe done by first opening main brake valve 53 to tighten assemblies ALand AR simultaneously on hoisting drum Zl and then allowing theoperating handle of this valve to return to neutral positionwhile valve55 remains closed. Inasmuch as main brake valve 53 is of the bleederregulator type, the return of the operating handle to neutral positionafter tightening both brake bands allows air to bleed from relay [9through pilot line63, double check valve 57 and pilotlinetl to To assurethat the the bleedeiizportzofrmain:brakewalves53rand this;- in:turn,.a'llows;&relay5-=valve? I9- to close and bleed airsfro'mpower-assembly. BL,v through branch line 28L, valve? body 2.9L, branchline vMIL and. from powerrassembly- BR.- -through..branch line 28R,valve: body; 29R-and branch" line 40R, thereby simultaneously releasingbrakeband assemblies AL and AR.

Operation ofweightcontrol unit II Imthetnormal .feed off operation ofbasic unit I, the'rate of feed-off is controlled by the setting ofneedle :valveIO. In the system of the present application, the settingof this needle valve' may beautcmatically; adjusted by, weight controlunit IIjin' accordance =with.the weight carried by'the drillingfgline.Whenv the; operator momentarily closes: feed-off starting, valvev 55,to: start the hoisting 'drumzto .rotateflzhe air. pressure-istransmittedznota only through. pilot line. 65, double checkvalve-204,pilotline 205, valve H and pilot line: Ir'IR'to insure the properpositioning of the valve elementsinmaster valve assembly C but, inaddition, is appliedthrough pilot lines 65 and 2.06:againstdiaphragm 24Iof double diaphragm valve Q, closing this valverand allowing air tobeibledfrom-pilot lines connected with its outlet so athatweig-ht-control-unit II is placed in operationand' against diaphragm 244of double diaphragm valve- S-to open this valve so that the pressure"inlthe steam chest line I38 has access to? the diaphragm I26 of valve Kand diaphragm I5I of valve M to put torque control unit V and pickupunit VI inoperation.

When weight control unit II becomes activated by theiclosingof valve Q,diaphragm valve I5 opens and compressed air flows from main air line 50through line I6 and valve I5 to branch line- I08'and valve. Band tobranch line I09 and valveflE; Thesupply of air to valves E and F causes:the -valveelements in these valves to reciprocate aswell. as thereciprocation of pistons IOI-in motor units GL and GR. Assuming that themovablevalve element 86 of valve E is in its left position,compressedair passes through line I08,- port83, passage 88, outlet port85L and line I05 where his applied through port 92R against valveelement 960i valve assembly. F and forces valve element vQiito itsleftposition. When valve element 96 of. assembly. Fis. in'its left positioncompressed. air. passes. through inlet line I09, port -93, passage 98and outlet port 95L through line. I041, andinto cylinder. I of assemblyGL. The. compressedair. supplied to cylinder I00 of unit GLnotonlycauses thepiston to reciprocate but in. addition,.passesthroughline ILwhere it is,appliedthroughport 82L of valve assembly EforcingmovableelementI-ZG to move from its left to. its. right. position. When thevalve elementBG moves. to its right. position compressed air i allowedto pass through line I08, inlet port 83,'.passage 88, outlet port 85Rand line I01 toinlet port 92L of valve assembly F and forces valveelement 95 of this assembly to its right p0- sition;,withvalveelement'sfi of assembly E in its rightp'o'sition', the port 92Rofvalve assemblyF istconnected through line I06, port 85L and-passage 80to exhaust port 84L which relieves the pressure on' theright end-ofthe'valve assembly Fallowing valve-element 96 to move to the right. Whenvalve element- 95 moves to'its right position'; compressed air passesthrough line- I09, port-93,- passage: 98"andoutlet port 95Rthrough line'IMR' to'unit-GR. The compressed air-'supplied t'o:unit GRjrnot only'causes the piston? I0'I in this' unit'i to reciprocate? but;intaddition, a

portionpasses .through .line I 05R .where..it-..is.ap+ plied throughport 82R. of .valve assembly. E and forces valve elementof valve E toreturn to its initial left position. As longas .compressed air. hasaccess'.to;valves. EJandF of weight control unit 'llthe'motors GL and.GR reciprocate continuously; As" long as. the weightsuspended fromdrilling'line22 remains withinthe' prede termined'rangazthe needle J of'weight'indicator, nottshown; remains "at :a mid-point position be-.tweenivalves'" IIOL. and IIOR and these bleeder valves are not opened.so that. the" air pressure in branch lines I I3 and I20 'remainsat aconstant value. Howevenwhen the weight carried by the" drilling linebecomes either-excessive or too light needle valve J moves away; from'its? midpoint position. If the weight 'carried' becomes lessthan-desired needle valve. J moves to the left so thatbleeder"valve IIOLstrikes the needle J each time the piston I0-I in.unit GL reciprocatesthereby bleeding air from line- II8 through bleeder valve. I IOLwhich,.in turn, actuates unit HRand'causes. the pawl'member II5 of thisunit to move' upwardly which,,in turn, moves valve wheel 12 in' thecounterclockwise direction. there by. openingj valve;10 and allowinganincreased flow ofhydraulic fluid...through lines. 41L and 41B". This.increasesithe 'rateof pay-01f of 'hoist ing H of basic assembly'LL Ifthe weight carried by the drilling line becomes excessive, needle Jmoves-to. the right. and bleeder valve IIOR' will strike. it each timepiston IOI of unit.GR reciprocates and thishin turn, will allow air to;bleed from unit HL through branchline I22L', line.I20 and bleeder valvelIOR.-tovreduce the air pressure in-the cylinderof unit'I-IL,,causing thepiston of unit HL toreciprocate which, in turn',.rotates valve wheel I2..of needle valve I0 in the clockwise direction to.v reduce the flowof"hydraulicfluid through line. ML and HR; this decreases the rate'ofirotation.offdrum 2| of basic unit I;

Operation of *quz'ck application 1 unit III The. quick application unit'IIIcooperates with the weight control unit II'and' basic'unit I. Withthe basic unit I'payingoutdiilling' linenormal feed-off operations and;with the-weight control unit II in command, if the drilling conditionsare such that the weight becomesless than desired, as When. the drillbit abruptly. passes from a hard formation to. a soft, easily drilledformation, the weightcontrol unitII attempts to-make a correction'in'that'needle J of the weight indicator moves to theJleft causingeachstrokeof air motor unit GL to bleed air'from bleederval've' IIOL'.The discharge. of air through bleedergvalve IIOL causes actuator "HRtooperate, each stroke of actuator HR causing. valve wheel I2 to movethrough a portion"ofarevolution. If the weight carried thedrilling-line: 22 does'not become normal after the air. has; been bled"through bleeder valve 01;. a givennumber.ofsuccessive strokes, ,thequickap'plication unit'III is caused tooperate. The quick applicationunit'III'.operatesatthis;timeibecause the air bled off through bleedervalve..l I 0LI.reduces..-the. pressure, in pilot line-.22 2.. andinthe.diaphragm of diaphragm valve 228sto .suchiamextent that..the.valve.element of valve 22 0 (notshown in .the drawing ismomenttarilymovedafrom .its rclosedn position. to .itsfull openipositionl and allows thy-,draulicsfluid to. flow through 5- theby-pass: line-.221 Thisimomentary openingsofcvalve 228 allowsthehoisting drumlj tof-rotate at an: increased. rate: which,..in.;ti1rn,QHOWSZhOIStHIE'IiIIBTzZLtO payout-"at-a-fastenrate o. l9 than .thatprevailing when valve 228 remains closed and the hydraulic fluid isallforced to flow through needle valve I0. With the pressure reduced inpilot line 222 as'described, the air supplied to branch line II8 throughthrottling valve II 1 issuch that subsequent successive strokes of airmotor GL causes throttling valve 228 to be momentarily open upon eachstroke of air motor unit GL until the weight carried by the drill stemincreases to an amount within the predetermined range and pointer Jreturns to its central position whereupon the bleeding of air throughvalve BL is stopped and the pressure in pilot line 222 and in thediaphragm of valve 228 builds up to its normal value and valve 228 thenassumes its normal closed position.

. 01mm of drill 017 unit IV The drill ofi unit IV also cooperates withbasic unit I and weight control unit II. Drill all unit performs aparticularly useful function when the drill passes abruptly from arelatively soft to a relatively hard formation, that is to say, when thenormal drilling speed must change abruptly from a relatively rapid rateto a relatively slow rate. In weight control unit II the air replacingthat bled off through bleeder valve IIilR is supplied from main air line50 by branch line H6 controlled by orifice or valve needle H1 and thencethrough branch line I20; drill off unit IV provides a supplementaryconnection by way of pilot line 2II controlled by orifice or needlevalve 2I8 and pilot line I24 controlled by valve 2I3. The flow areas ofvalves 1, 2I8 and H9 are so proportioned that the air bled off throughbleeder valve I IOR after a certain number of consecutive strokes, saythree strokes, lowers the pressure in the diaphragm of diaphragm valve Tsufficiently to allow valve T (which is normally closed) to open which,in turn, causes air to flow through line 2I5. valve T, line 2 I6, doublecheck valve I32, line I33, double check valve I34, line I35, and fromline' I35 to branch lines |35R and I36L to the diaphragm of valves I3'IRand I3IL, respectively, and through pilot line 22! to the diaphragm ofdiaphragm valve I23. The compressed air applied against the di-aphragmsof diaphragm valves I23, I3IR and I3IL causes these valves to close. Theclosing of diaphragm valves I3'IL and I3'IR stops the flow of hydraulicfluid in basic system I and prevents feed-off of drilling line 22. Theclosing of valve I23 prevents the actuator HL from operating as air isbled from bleeder IIUR with each stroke of air motor GR. Thus needlevalve I of the hydraulic system is not progressively closed bysuccessive strokes of air motor GR if a long periol of time is requiredto deepen the hole enough to reduce the weight on the drill bit to thepredetermined range and at the same time hoisting drum 2I is heldagainst rotation to allow the drill bit to drill off. The valves I3'IRand I3IL and valve I23, after they are once closed, are heldin thisposition by subsequent strokes of air motor GR actuating bleeder valveIIIlR which keeps the pressure applied against the diaphragm of valve Treduced until such time as the desiredweight on the drill bit has beenreached. When the weight on the bit is reduced to the predeterminedrange, pointer J resumes its central position, this brings it out ofcontact with bleeder valve I IllR and stops the bleeding of air throughvalve IIOR which, in turn, allows pressure to build up in pilot line I24whichallows diaphragm valve T to close. Valve T is of the bleeder typeso that when it closes air is bled to the at mosphere from lines 2I6,I33, I35, branch lines I36L, I36R and pilot line 22I and this reductionin the pressure allows valves I3IR, I3'IL and I23 to open. With theopening of the valves I3'IR and I3IL and I23 the weight control systemII is again in command.

Operation of torque control unit V It has been heretofore explained thatthe operator puts the system in operation for feeding ofi the drill line22 by momentarily opening feed on starting valve 55. The momentaryopening of this valve allows air pressure to be applied againstdiaphragm 244 of double diaphragm valve S opening this valve andallowing the pressure in steam chest line I38 to be applied against thediaphragm of double diaphragm valve K of the torque control. As long asthe torque exerted by the drilling engine as indicated by the pressurein the steam chest line I38 is less than a. predetermined value, thetorque control unit V remains inactivated. However, when the torqueexerted by the drilling engine reaches a predetermined value, thepressure in the steam chest line increases to a predetermined value andthis increase pressure applied against diaphragm I25 of double diaphragmvalve K causes this valve to open thereby allowing compressed air topass from main air line so through branch line I28, double diaphragmvalve K, double check valve I36, and pilot line I3I. The pressureapplied through line I29 to double check valve I30 serves to block offdouble diaphragm valve Q while the pressure transmitted through pilotlines I3I and MI to the diaphragm of diaphragm valve I5 closes thisvalve; this arrangement insures that weight control unit II and itsauxiliary units, quick application unit III and drill off unit IV, areinactivated and that torque control unit V is in complete command atthis time. The air pressure in line I3I also passes through double checkvalve I32, line I33, double check valve I34, line I35 and branch lineI36R and I36L to apply the pressure against the diaphragm of diaphragmvalves I3lR and I3'IL, closing these valves which, in turn, stops flowof hydraulic fluid through lines 41R and ML, thereby stopping allrotation of hoisting drum 2|. The pressure in pilot line I35 is alsotransmitted through pilot line 22I and closes diaphragm valve I 23 ofdrill oii unit IV; however, this makes no difference one way or theother because this unit is inactivated. Valves I3IR and I37L remainclosed as long as the torque exerted by the drilling engine is greaterthan a predetermined value. When the torque exerted by the drillingengine becomes less than said predetermined value the pressure exertedagainst diaphragm I26 of double diaphragm valve K decreases so that itis overcome by the constant pressure valve applied against diaphragm,IZ'I of the double diaphragm valve K through pilot line I39 connectedthrough regulator I43 to compressed air main 58. Double diaphragm valveK is of the bleeder type and upon closing air is bled to atmosphere fromlines I 3!, I33, I35, I36R, I36L and from the diaphragm of diaphragmvalves I3'IR and I3'IL, allowing valves I 31R and I 31L to open andhydraulic fluid to circulate through line I3'IR and I3IL. The airpressure is also bled oil through pilot line I4I from the diaphragm ofvalve I5 thereby allowing this valve to open and weight control unit IIto again assume command of the system.

mam-Mr Operation-.01 pickup-assembly VII;

Whenthe'torqueexertedby the drilling engine exceeds a predeterminedvalue,; which value is greater" than that required. to activate torquecontrolunit V-, the pressure increases in steam chest line 38 to such anextent that the pressure exerted oil-diaphragm" IEIof doublediaph'ragm-valve-Mbausesthis valve to open so that thepicliup assemblyV1: isactivated? In other words, partsof the entire system arecoordinated so that torquemontrol unit Vis-first' activated'to stopfurther payoff of" the drilling line 22 and if 'this operation isinadequate and; the torque increasesthen command is assumed bypick upassembl'y VI; Since-torque controlunitv'haspre viously. had command;weight control unit" II and itssa-uxiliary: units quickapplication: unit111 and drillofi-unit IV; have beeninactivated'; valveK of-"torquecontrolunit V remains open :so" units II; III and IVremain inactivated.when pickup assembly- VI assumes command.

The openingofdouble diaphragm valve M allows air to pass from main airline 53, through pilot line-I53; valve M"; pilot linel'5 lidouble checkvalve-l55; pilot line I51 to pilot-line: I58 where thestream of air issplit-with one portion passing through double-check valve I34 to"pilot-line" I35. This-portion going to pilot line I 35 will normallymerely maintain part -of the--syst'emin-tli'e state it was placed by"the torque controliunit V when it was: command; namely, the maintenanceof pressure against the diaphragms of diaphragm valves I31R'and- I 3 'ILto=prevent the-flow of-fiuid through needle valve I ll of weight controlunit" II. The other-portion of the compressed air." distch'arged topilot line I'58"-serves to activate several units-. Ainpressureappliedto the diaphragm of diaphragm valve I59 causes this valve to openwhich", in turn, allows compressed air to" pass frommain line 56 topump: P thereby. supplying power to the pump and-causing jit to beginoperation.- The compressed airfis' transmitted from pilot lineI58-through pilot. line: I64 where, it: is exerted against the diaphragmof diaphragm valve I63 causing this VaIVBilJO open. The.pressure-exerted from pilot line I '8'is also transmitted throughbranchpilot line I61; through port I'II ofmaster valve N where it isapplied against the right'end of movable: valve element "I16 of valve Nand forces-thiselement'to-move' to itsrleft position where-it is held bythe. air pressure continuously exerted through pilot line I61; Themes.-sureinpilotline -lfihis .exertedagainst the dia;-

I GG-and causes this valve to open. .and is exerted againstthe diaphragmof diaphragm valve- I68 through pilot" line I69 and causesv this..valve. to open. Compressed. air. flows momentarily from pilot line I58through'pilot line 200, normally open diaphragm-valve I 68; pilotlineZ01 double check valve-202, pilot" line 20.3; double check-.valveifld,and-pilotline 205; where the stream is.,split', with aportion-passingthrough pilot line. ZGBjcontrolled by diaphragm valve I68and applying pressure through port I82 of valveiOito iorce.element.l88to'its right positiQn and the other portionv passing through valve N,and 'pilotline I'IL whereit is applied through por-t 38L of master;valve'assem- 1315! C and forces members 39L..and 30R. of this assemblyto their extremeright =positions. At .the same: timev air begins to:flowthrough normally open-valve. I60 it also; passesthrough pilot'lineJ61 and:.leaksthrough. orificeuor. needle valve;- I 62 to. the diaphragmof diaphragmtvalve I 60 .assoon as;thesair:leakingthrough needlevalyezi62.abuilds urn sufficient; pressure. it: closes diaphragm valve I60which is of the bleederrtypeand bleeds off air pressureirom; lineZIlIvso that the air pressure thereafter.passingthrough.double1check-valve-2I'I2 is controlledby pilot valve 68L. In.other-words, valve I 60 insures proper positioning; of the-valveelements in: master valve 0 and master valve-assembly C when pickup unitVI takes command.

The; manner inwhichthe master valve assembiy;-C of unit I and-mastervalveO=of pickup unit IV are synchronized whenpickupunit V1 isac"-tivated willbe seen by tracingthe flow as follows: Assume valve elementI88 of .valve 0 and valve elements.-.3BL..and 30R of master; valveassembly C. are in their right positions; These valveele: ments may be 2thus positioned by: the momentary flow of air through' valve-| 60whenactivatinggthe pickup .unit; VI.or after, the unit has been put intooperation, by contact of activator. 49L with feed.- off. valveJZBLwhichmomentarily opens valve 48L andvallows compressed. air. to passfrom mainair line-.50 through branch. line 5| line. 52L, valve 48L,piiot line 66,;double checkvalve 202, pilot line .203, double: check.-valve 294 and pilot line 2fi5pwhere the airstream: is -split,, oneportion passing through pilot line-209 andend port I82'of valve 0toforce movable valve element I88 to theright while-theother portionofthestream entersvalve N through inlet port I13 and leaves throughout.- let-lport I-l2= passing, through pilot line IIL; and imposing:pressure. on master valve assembl-y 'C through end port 38" toforce'the' movable valve elements 39L. andQBR, of master'valve assemblyC totheir extreme'right positions. With movable parts 36L andSIJR of.master valve assembly 0 to their extreme; right positions, compressed;air from. the .main air line a can .enter. power. assembly BRv so thatbrakesbandzassembly ARisgtightened on. thehoisting drum 2 I... while;air: is.bled.. from the atmosphere. frompower assembly BL causingassembly AL to be released. The. movement. of movable-part I 88 I of.valve 0. toaits rightposition allows hydraulic. fluid. to': be forcedby) pump P through line 2 I4, diaphragm valve I63 and hydraulic line:A'IR- where. it is. applied to the piston end of cylinder MR, causingthe piston 42R to::be -f0rced downwardly pulling with 1 it the brake:band-1 assemblyAR which is tight: on the drumZI- and pulls the drum withit.. As the piston 42R reaches-theendoiits stroke, activator 493;.contacts.- ieed-ofi valve; 48R. which allows compressed" air to.passthrough. pilot line. 2, port I75, passageJ'Ia and toport II i'of.valve-N, the..--stream.- is then. split with. a portion. flowingthrough. pilot line: 2.12. controlled: by, diaphragm valve-.- I65-andimposing a-. pressurea'gainst. the rightendofvmaster valveO causingmovable elee ment'; I88. of thisvalve-to move to its-leftposition'while-the. other portion oithesplit stream passes through pilotline I 'IRandimposesa pressure throughendportttR of master valveassembly. C. causingi movable parts 30L and 30R of mastervvalveassemblyC tomove-sto their extreme left positions. The movement of parts'wLand3&R of master-valveCto their'leftpositions-allows airrpressureito: enterpower assembly BL thereby tightening; brake. band: assembly ALonzhoisting drum 2i and at thesame time bleeds air'from power assemblyBR- thereby releasing brake band assembly A-Rirom the drum.Simultaneously with .the tightening: ofbrake band assembly AL onto.thedrum, the-1 movement a of movable valve element a I B8.of-. master:valvezO to its; left position allows hydraulic fluid-:to; be: Dumped by;pump P

